This application is a request to purchase a MoFLo high speed multilaser cell sorter in support of 33 users who are dependent upon longstanding shared resource cytometry facilities at the University of Washington. This user group is presently services by closely interacting resource facilities located in the Departments of Pathology and the Department of Environmental Health. The Department of Pathology facility, directed by Dr. Peter Rabinovitch has used a Coulter Elite Cell Sorter since 1990. The Department of Environmental Health facility, directed by Dr. Terrance Kavanagh, has utilized an Ortho SOH cytometer which has become inoperable over the past year. Cytometry usage is also facilitated by four separate Program Project and Center grant Cytometry Cores directed by Drs. Rabinovitch and Kavanagh. There is a great need for new instrumentation because 1) there is much greater demand for flow cytometry services than can be met with existing instrumentation; 2) there is a need for a more dependable and flexible instrument for multilaser analyses; 3) there is a need for higher speed analysis and sorting. The present excess demand for access to flow cytometry and the need for additional capabilities, including high speed sorting, are now limitations to the progress of many NIH funded research projects at the University of Washington.